Electric flat-iron.



R. BOOMBB. ELECTRIC FLAT IRON.

APPLICATION FILED N0\T.11I 1912.

y Patented Apr. 29,1913.

W/TNESSES.'

RL C/Zardaw?? el;

AT! Ey ter portion of the iron, due to/the construction of the heating element in such a manner y UNITED sTATEs PATENT oEEICE.

, RICHARD RooMER, or DETROIT, MICHIGAN, AssIG'NoR To FLORENCE ELECTRIC TRAY COMPANY, oF DETROIT, MICHIGAN, -.a CORPORATIONy or ILLINOIS.

ELECTRIC FLAT-IRQN.

' l Speineation of Letters Patent.

Patented Apr. 29, 1913.

Application led November11,.19r12. Serial fa/730,659.

T0 all whom itmayvconoem:

.Be it known that I, RICHARD BooMER, a cltlzen of the United States, residing at De- Michigan, have invented certain new and useful Improvements in Electric Flat-Irons, Aof which the following is a speciiication.

Thisinvention'relates to fiat-irons heated by means of electric current, and its object is to provide a device of this characterv with a novel heating element which is so constructed that it shall not burn out, even if the electric current should be accidentally left on toheat the iron as a Whole beyondthe limit of utility.

The invention has furthermore for its object the provision of a flat iron in which 'the base plate isV heated substantially uniformly over its entire surface so that in this manner the heel as welll as the toe portions will be at the sametemperature as the cen- -that the loss of radiation at the heel and toe portions will be compensated for by in-4 vcreasing the heatproduclng -,qualities of the heating unit at those points when compared with the center or intermediate portion of the iron. p c

The invention has also for its object a flatiron, so constructed that the shellY may contain different thicknesses of metallic Weight plates which are interchangeable so that the same iron may be decreased or increased in weight according fto the Work to be performed.

Further objects of the invention will hereinafter appear and be defined in the claims. The invention has been clearly illustrated ink the accompanying drawings, in which' similar characters denote similar parts and in which- A Y Figure 1 is a top view of the base. 'of the iron broken away to show the several layers ofthe unit. Fig. 2 is a central longitudinal vertical sectionof the same.S

Briefly stated, my improved iron comprises a shell having a base plate 10 and side walls 11 which converge toward the point 12 and a top plate 13, thus forming a chamber 14 which is open at the-rear or heel of l the iron so that the heat unit may be read-v y the chamber 14 beingxcored. troit, 1n the countyA of Wayne and State of V ily laced therein' or removed therefrom. Pre erably all these parts are cast integrally,

screws 17. l' The heatunit which constitutes a part of p the present invention is formed by a central plate 20 of (inica or other heat-resisting and lnsulatlng material around which a heat `resistance wire or tape 21 is wound into conrvolutlons the spaces between vwhich increase progressively toward the center portion of the plate 20 from the ends. This fact is Important for the reason. that by this construction I am enabled to distribute the heatproduced by the electric current in the vresistance" wire 21, substantially uniformly throughout the entire surface plate 10 ofthe iron, a desirable quality very often lost sight of for in most, Cases the heel or toe portions of the iron are less hot than the center portion, due to the greater 'radiation of heat at those points than inthe center. For this reason the convolutions' in my present iron are nearer together in these portions than in the center. In other words I generate more heat at those points so that consequently, if more heat i's'lost by radiation, yet the increased number of convolutions of the conductorewill compensate for Mthis loss in proportion. This loss by radiation varies with the' shape of the iron, but in all irons having the samel shape of basethis lossf will be substantially the same, and lin order to preserve the standard of the convolutions or winding @f the conductor, the mica plat/es are stamped out so as to have notches, 20 at their edges 'so that the conductor' may be readily wound thereon, and all the heatingnnits therefore be of un1form capac1ty. Inasmuch as the resistance wire 1s preferlSli ablyl in the form of-a flat tape, and the central sheet' 21 is comparatively thin, the tape will, although it may have only a very short bend at the edges of the plate, yet be loose in the notches. The` Winding itself is a comparatively easy process, and after the tape has been wound onto the plate, its short bends at the edges of the plate can Areadily be flattened with a hammer so that the inside bend of the tape, a feature which is advantageous for the reason that experi- I ence has demonstrated that when such tape is heated and then allowed to cool, a certain amount of shrinkage in the tape will result, or `in other words the length of each convolution will, after its iirst heating, bea trifle shorter than it was originally. The looseness or leeway above mentioned will therefore allow for the shrinkage without breaking or buckling the-edge of the mica plate, or straining of the tape. Subsequent heatings vand coolings of the t-ape will have no, further effect yas far as further shrinkage is concerned.

The winding of the tape begins at the terminal 25, and the several convolutions are laid into the notches 20 above mentioned i until the toe portion is reached whereupon 28 of insulating material, which 1n turn the tape is returned to the heel portion over a plate 26 placed above the several convolutions so that no short circui'tmay exist between the return stretch of the tape and the convolutions, the end of the return stretch being connected to a'terminal 27, and both terminals 25 and 27 being secured in a block is firmly held in place by a back-plate 29 which constitutes a part of a presser or weight plate 30 extending into the chamber 14 and covering the entire surface of the unit and the protecting mica plate 26 above referred to.V A plate 35 of mica or other insulating material isy interposed between the bottom `of the heating unit. and the upper face of the base of iron.

In orderto establish va close contact between the unit and the base of the iron, and also to still further increase the insulation of the unit from the weight plate 30, I employ a protecting sheet 26 of mica or similar material and also a thick sheet of absorbent paper 31 which is thoroughly impregnated with cement and in soft condition when placed into the iron when itlis first built up. On the other hand this paper may be dispensed with, if desired, and 'a layer of cement substituted therefor, the function of the paper simply beingl that .of holding the `cement together and against crumbling. As

soon as heat is'given to the unit, the cement Iwill naturally dry out and become, stonelike in its nature, and it will have its lower surface in full surface contact with the mica sheet regardless lo-f its undulations. At the same time its upper surface will be `flat against the plain under face of the weight plat-e 30 abovementioned.

In order to produce thedesired result just described, it will of vcourse be necessary to exert pressure upon the weight plate, in the first place, force screw32 in threaded engagement with the top pla-te 13 and'having a head 32 disposed within. the space beneath the lhandle strap 16 and aodapted to be operated by a wrench side. Y

As a' further precaution against short circuiting the terminals 25and 27, a plate 33 of insulating material may be placed within the notch Slttprovided in the heel portion of the weight plate for that purpose.

From the above it vwill be obvious that, according to the size of the chamber `14, weight plates ofl different thicknesses may be substituted for the one weight of the iron be therefore increased or decreased accordingly. Furthermore, inasmuch as the heat generated depends entirely upon the number of convolutions of the reand I accomplish this result by a` which. can be inserted from' either shown, and the sistance tape, units containing differently spaced windings may be used in conjunction with these different-weight plates so that all thedesired conditions may be met without substituting a new shell for thec one employed and which the operator is used to,

yit being furthermore obvious that the expense of supplying these interchangeable parts in connection with the same case, Will be comparatively low when compared with the, cost of supplying a new iron for each particular purpose needed.

-I claim l 1. The combination of\a heating unit comprising a plate of insllating material `having notched edges, a flat metal tape loosely wound around the plate and having its bends flattened so as to permit movement in said notches, guardplates of insulating material above and below said tape, and a cast iron plate in contact with one of said guard plates and provided'with a pocket in one end, a block of insulating material in said pocket, and electric conductors mounted in said block and connected to the ends of said tape.

2. yThe combination of a heating unit comprising a notched plate of insulating material, a resistance Wire loosely wound around' the same, guard plates of insulating material disposed above and below the convolutions of the resistance wire, an independent and interchangeable Weight plate disposed above the unit and having a pocket in its rear end, a block of insulating material mounted on the rear end of the heating unit in said pocket, Land contact members mounted in-said block and connected to the resistance wire.

' 3. The combination with a heatingy unit adapted to be placed within the chamber of a fiat-iron and having the ends of the resistance wire extending from its rear end, a

block of insulating material mounted on the rear end of'the heating unit, contact members mounted in said block and connected to members will be heldin position in the flatsaid ends of tie resistance wire, a presser iron. y10 plate extending over said heating unit and In testimony whereof I aHiX my signature having a pocket in its rear end to receive in presence of two witnesses.

and hold said block, and adapted to be held RICHARD BOOMER. in position by a screw mounted in the top of Witnesses: theAiat-iron whereby the heating unit, the- FLORENCE L. CROMBIE,

v block of insulating material -and the Contact CHAs. F. SoinunLz. 

